Abstract
Purpose: :
To report the phenotypic and genetic characterization of a new mouse mutant with a cone function loss, cpfl5, that is associated with the migration of cone somata into the outer plexiform layer of the retina. cpfl5 is a new, naturally occurring mouse model of autosomal recessive achromatopsia as defined by a missense mutation on the Cnga3 gene.
Methods: :
The retinal phenotypes of cpfl5 mice were studied using serial indirect ophthalmoscopy, electroretinography (ERG), histology, and immunohistochemistry; genetic analysis included linkage studies and gene identification.
Results: :
Mice homozygous for the mutation showed no cone ERG response. Histological and immunohistochemical analysis revealed the migration of cone somata into the outer plexiform layer of the retina from as early as postnatal week 3. Genetic analysis showed that cpfl5 is autosomal recessive and closely linked to the marker D1Mit71 and the gene encoding the cyclic nucleotide–gated (CNG) channel subunit A3. Sequence analysis of the candidate gene recognized a missense mutation in exon 5 of the Cnga3 gene.
Conclusions: :
Mutations in the A3 subunit of the CNG channel cause autosomal recessive complete achromatopsia. Cone somata migration also indicates that the Cnga3 gene is responsible for retinal cone location. A naturally arising mouse Cnga3 mutation provides a good model for studying the pathology of human CNGA3 mutations and the role of the cyclic nucleotide–gated channel in cone signal transduction.
Keywords: gene mapping • retinal degenerations: hereditary • genetics